IB/rdmavt: Add support for tracing events

This patch adds support of tracing events using the kernels built-in event
tracing infrastructure. This can be extended to provide a wide range of
trace and debug capabilities which have a negligible impact on performance
when enabled. These should be preferred over the use of the rvt_pr*
functions.

Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>